Abstract
Human cellular Kirsten ras1 and ras2 genes were localized to chromosomes 6p23 ----q12 and 12p12 .05----pter, respectively, using human-rodent cell hybrids. Thus, the short arms of human chromosomes 11 (encoding lactate dehydrogenase-A and the proto-oncogene c-Ha- ras1 ) and 12 (encoding lactate dehydrogenase B and c-Ki- ras2 ) share at least two pairs of genes that probably evolved from common ancestral genes.